3 Ways To Use React Hook Form Onchange Setvalue

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In recent years, React Hook Form (RHF) has become a popular choice among developers for handling forms in React applications. Its simplicity, flexibility, and ease of use make it an ideal solution for managing form state and validation. One of the key features of RHF is the useForm hook, which provides a straightforward way to manage form data, errors, and validation.

One common use case when working with forms is the need to update form values based on user interactions, such as selecting an option from a dropdown or checking a checkbox. In this article, we will explore three ways to use React Hook Form's onChange event to set values in your forms.

Understanding the Basics of React Hook Form

Before diving into the onChange event, let's quickly review how RHF works. When you create a form using RHF, you wrap your form component with the FormProvider component and pass the methods object to it. This object contains several useful properties and functions, including register, errors, and reset.

The register function is used to register form fields, which allows RHF to track their values and validation status. You can use the useForm hook to access the register function and other form methods.

import { useForm } from 'react-hook-form';

function MyForm() {
  const { register, handleSubmit, errors } = useForm();

  const onSubmit = async (data) => {
    // Handle form submission
  };

  return (
    

      
      
      Submit
    
  );
}

Method 1: Using the `setValue` Function

One way to update form values using the onChange event is by using the setValue function provided by RHF. This function allows you to update the value of a registered form field programmatically.

To use setValue, you need to access the methods object from the useForm hook and call the setValue function with the name of the field you want to update and the new value.

import { useForm } from 'react-hook-form';

function MyForm() {
  const { register, setValue, handleSubmit, errors } = useForm();

  const handleSelectChange = (event) => {
    setValue('selectedValue', event.target.value);
  };

  const onSubmit = async (data) => {
    // Handle form submission
  };

  return (
    

      
        Option 1
        Option 2
      
      
      Submit
    
  );
}

In this example, when the user selects an option from the dropdown, the handleSelectChange function is called, which updates the value of the selectedValue field using setValue.

Advantages and Disadvantages

Using setValue provides a straightforward way to update form values based on user interactions. However, it requires manual handling of the onChange event, which can become cumbersome when dealing with complex forms.

Method 2: Using the `useWatch` Hook

Another way to update form values using the onChange event is by using the useWatch hook provided by RHF. This hook allows you to watch the value of a specific form field and execute a callback function when its value changes.

To use useWatch, you need to import the hook from RHF and pass the name of the field you want to watch and a callback function.

import { useForm, useWatch } from 'react-hook-form';

function MyForm() {
  const { register, handleSubmit, errors } = useForm();
  const watchedValue = useWatch({
    name: 'watchedField',
  });

  useWatch({
    name: 'watchedField',
    control: 'anotherField',
  }, (anotherFieldValue) => {
    // Update another field value based on watchedField value
  });

  const onSubmit = async (data) => {
    // Handle form submission
  };

  return (
    

      
      
      Submit
    
  );
}

In this example, the useWatch hook is used to watch the value of the watchedField field and execute a callback function when its value changes.

Advantages and Disadvantages

Using useWatch provides a declarative way to update form values based on user interactions. However, it requires careful handling of dependencies and can become complex when dealing with multiple watched fields.

Method 3: Using the `useForm` Hook with `getValues`

The third way to update form values using the onChange event is by using the getValues function provided by RHF. This function allows you to get the current values of all registered form fields.

To use getValues, you need to access the methods object from the useForm hook and call the getValues function.

import { useForm } from 'react-hook-form';

function MyForm() {
  const { register, getValues, handleSubmit, errors } = useForm();

  const handleInputChange = () => {
    const currentValues = getValues();
    // Update form values based on currentValues
  };

  const onSubmit = async (data) => {
    // Handle form submission
  };

  return (
    

      
      
      Submit
    
  );
}

In this example, the getValues function is used to get the current values of all registered form fields when the user interacts with the form.

Advantages and Disadvantages

Using getValues provides a flexible way to update form values based on user interactions. However, it requires manual handling of the onChange event and can become complex when dealing with large forms.